Recently, by mounting radar devices on vehicular objects such as motor vehicles, and by detecting radar reflectors such as obstacles in traveling directions, developments are carried out so as to realize those functions for velocity controls and collision prevention. In these radar devices, because a radar reference axis becomes misaligned off an originally presumed direction, a problem can be raised in that an azimuthal angle with respect to a radar reflector obtained as a result of processed radar signals becomes not correct.
These kinds of offsets of the reference axis are caused by poor accuracy of an initial work done when a radar device is mounted on a vehicular object. Moreover, even if at an initial stage the radar device is mounted on the vehicular object with high accuracy, there exist cases in which the reference axis becomes misaligned with actual use. Because, correctly observed values can not be obtained from the radar device under a state in which the reference axis becomes misaligned, contribution to increased safety can not be made.
As a consequence, such technologies are proposed as to adjust the reference axis of a radar device mounted on a vehicular object to a traveling direction of the vehicular object (for example, in Patent Document 1). These are proposed for estimating a direction of the reference axis by using velocity information on a vehicular object mounted with a radar and observed values of reflection points, which are primarily stationary objects.
(Patent Document 1)
Japanese Patent Laid-Open No. 2002-228749, “On-Vehicle Millimeter-Wave Radar Device”